I'm looking to create a (probably 10 level) PRC with my DM that improves both Binder soulbinding, paladin casting and the paladin mount. If I could, I'd probably take the Knight of the Sacred Seal saves and BAB progression and use that and the logical followup.

What's Homebrew Design's thoughts on the cheese-o-meter? Should I add in the Smite Evil progression etc. or drop something?

Yes, I'm using the 3.P Paladin and the 3.5 Binder, we'll work out an updated Binder to fit the Pathfinder updates.

Also, any thoughts on the balance if my DM allowed me to Smite Chaos rather than Evil?